They say blood is thicker than water.

North Wales, Boxing Day 1987. Two children are dead: one an infant, found at the site of an ancient copper mine on the Great Orme, the other a young girl, her body laid out in a stone circle.

DI Emma Grey's investigations uncover buried truths, old passions and even older hatreds. Her inquiries lead her to the Morris sisters, each with a story to tell. Just as the long stones keep secrets, so the Morris sisters keep theirs, even from one another.

As Emma works to unravel the mystery, aided by her irascible boss, DCI Aled Watkins, she finds herself haunted by thoughts of the children, compelled to put their spirits to rest.

Who are they? Are their fates connected? And can any secret really be kept forever?